The Shop > Metal Stuff
Sawed off cupola
vtsteam:
--- Quote from: RobWilson on June 16, 2013, 04:22:05 AM ---Hi Steve
Thats a nice compact set you have there :thumbup: , thinking of doing similar , due to space and cost of fuel gas .
I may go down the Propane route too . Rob
--- End quote ---
I like propane a lot, Rob, now that I've tried it. Took me a bunch of cuts to understand the difference. Preheat is a little longer, but not much -- but you do need to keep the flame about an inch above the cut to preheat, not touching the blue cones as in Acetylene.
But you lower when you hit the oxygen to normal cutting height -- didn't realize that at first and so was interrupting cuts. Makes sense now because, of course it's the oxygen jet that cuts, not the propane (or acetylene).
I like the compactness of the rig, too -- and there is 170 cu ft of propane in there instead of the 40 cu ft of acetylene in the B size tank that matches the oxygen tank. Plus propane is 2500 btu/cu. ft, and acetylene is 1750 btu/cu ft. Costs the same to fill the propane tank as the B size acetylene tank, and much more widely available. Also just a lot more stable a gas than acetylene, with its tricky storage medium and critical flow rates. so generally I feel better about just having a tank of it around.
Changeover for me was just buying a T rated hose ($35) and a propane cutting tip for my torch ($15). I had a spare acetylene gauge which I'm using. I've kept my acetylene tank in case I want to flame weld, but if that doesn't happen often enough, I'm thinking about trading it in for a second oxygen tank.
vtsteam:
I got a chance to work on a tuyere for the cupola today. I took an old piece of 2" pipe with an elbow attached that I had found half buried in a field . It was well rusted together, and filled with dirt. I sawed off the pipe to a 3" stub. Then welded a bandsaw cutoff from a 1-1/2" pipe with threads to the elbow. That made it into a Tee and will serve as a peep hole. I cut out the connecting hole through the elbow inside the new fitting using the oxy- propane torch.
Then I bent a piece of 1/8" plate to fit the barrel curvature, and burned a hole in it. I then welded the tuyere to the plate. The plate will serve as a mounting flange to attach to the furnace barrel. The barrel skin is very thin stainless and I'll probably rivet the tuyere plate in place. This is what it looked like, and a pic of test fitting it in place on the furnace. It isn't attached yet. A thunderstorm came up and I had to get tools under shelter.
vtsteam:
Riveted the tuyere on tonight and patched the lining and lid.
vtsteam:
Sunsine!!! This morning I decided to try to fire the patched lining and lid, and to do that I would try using my new propane burner. I took the oxy bottle off of the new propane cart and wheeled it up the hill to the furnace position in what was once cleared dirt, and more recently, mud. But today with the sunf and a breeze, the mud dried up.
To fire it I also needed a prop to keep the cupola doors shut, so I welded a length of chain onto a section of 2" pipe, and scrounged a square of 1/4" plate as a base. I didn't weld this to the pipe because I think it would more likely hang up that way.
Anyway, I got everything set up, dialed 5 PSI on the gauge, which seems to be a nice even flame for this burner. The Mako burner, which this one is similar to, has a range of 5 PSI to 15 PSI. I wasn't in any hurry to fire the lining, and I've never had it up to 15.
I just propped the burner in the cupola's tap hole and there was a muffled roar, much quieter than running a blower with charcoal. I figured I'd run it an hour.
vtsteam:
Naturally as soon as you start heating up a furnace, you think, why not use that heat? I didn't have a mold ready, and the sand isn't in condition anyway, but I figured I might try to melt a chunk of aluminum that has been a challenge to my bandsaw. Not the best stuff for casting -- 6061 t6 I think, but I might be casting some flasks like ironman's, and surface finish wouldn't be important. Some of the best structural aluminum types are not too pretty when cast.
Anyway I figured I'd take this recalcitrant 4 pound chunk and see whether I could reduce it to muffin ingots. The darn thing would hardly fit in the pot!
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